1. Field of the Invention
This invention relates to an improved combination belt and pulley used in a belt drive mechanism.
2. Description of the Prior Art
So called V-belts and multiple groove belts have heretofore been employed in conjunction with pulleys for power transmission purposes. One such V-belt pulley is disclosed in U.S. Pat. No. 3,225,614. In many cases the belts are not of V-section but are of trapezoidal section, and have a number of ribs across the contacting surface of the belt which are seated in and engage grooves in the pulley. Such a multiple rib belt and pulley arrangement is disclosed in U.S. Pat. No. 2,728,239. These belt and pulley mechanisms have been used for driving the rotatable horizontal axis drum of laundry machines such as automatic clothes dryers. The pulley is of small diameter and driven by an electric motor with the belt wrapping around the clothes dryer drum which is substantially larger in diameter than the pulley so that the drum is driven at a speed much slower than the drive pulley. Multiple groove or poly-V-belts, as they are often called, have been utilized for this purpose as they have been found to perform quite well with a minimum of slippage due to the poly-V configuration and mating of the spool of the pulley. Because the pulley is quite small in diameter relative to the drum, good traction between the belt and pulley is needed for power transmission. Moreover, the use of poly-V belts result in a belt of smaller overall dimensions for a predetermined power capacity.
One of the difficulties, however, in the utilization of a poly-V belt and pulley mechanism is that during the assembly of the mechanism there may be misalignment of the belt ribs to the drive pulley grooves. When this occurs the operation of the belt and pulley mechanism is detrimentally affected by the additional stress on some of the ribs which in turn reduces the belt life and induces a change in the speed of the driven item, such as the clothes dryer drum. In addition, such misalignment condition can cause the belt to actually come off the pulley and make the drive mechanism inoperative.
It is desirable to be able to have a poly-V belt and drive pulley mechanism that will automatically compensate for any misalignment of the belt ribs in the proper mating pulley groove and in addition prevent the belt from coming off of the pulley should there be any such misalignment.